The Runscope iOS Sample Code by Runscope shows how to debug and test API services. Examples include NSURL connection, AFNetworking, RESTKit, and ASIHTTPRequest. Library documentation available with additional lines of code.
Dipity is an innovative web service that lets users create interactive multimedia timelines for anything from breaking news to Internet Memes. But the real action is behind the scenes with their extensive web service, which allows third parties to build and manage timelines programmatically (our Dipity API profile).
The InternetDJ API opens this electronic music site to your app. Since 1997 (not a typo!) composers and fans have been able to share and mix music and videos. According to the API's website, requests are limited to 5,000 a day, responses are in JSON and an auth key is required.